Tension mechanism for spindles of metal-working machines



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Patented Apr. 13, 1886..

ATTORNEYS.

E m j J. HARTNESS.

TENSION MECHANISM FOR SPINDLES OF METAL WORKING MACHINES.

(No Model!) UNITED A STATES PATENT OFFICE.

JAMES HARTNESS, OF TORRINGTON, CONNECTICUT.

TENSION MECHANISM FOR SPINDLES 0F METAL-WORKING MACHINES.

SPECIFICATION forming part of Letters Patent No. 339,882, dated April 13, 1886.

Application filed October 9, 1885. Serial No. 179,438. (No model.)

To all whom it may concern.-

Be it known that I, JAMES HARTNESS, of Torrington, in the county of Litchfield and State of Connecticut, have invented a new and Improved Tension Mechanism for Spindlesof MetalWVorking Machines, of which the following is a full, clear, and exact description.

This invention relates to certain new and useful improvements in spindles used in work ing metal; and the object of my invention is to provide a new and improved spindle which is to be so constructed that it will give or yield when the strain on the tool approaches the breaking-point of the tool, but will not yield until this point is almost reached.

The invention consists in the construction of parts and details and combinations of the same, as will be fully described and set forth hereinafter, and pointed out in the claims.

Reference is to be had to the accompanying drawings, forming part of this specification, in which similar letters of reference indicate corresponding parts in all the figures.

Figure 1 is a longitudinal sectional elevation of my improved spindle. Fig. 2 is a crosssectional view of the same on the line a: a, Fig. 1. Fig. 3 is a cross-sectional view of the cam-plate on the line 3 3 Fig. 5. Fig. 4 is a side view of the key. Fig. 5 is a top view of the cam-plate. Fig. 6 is a cross-sectional view of the same on the line zz, Fig. 5. Figs. 7 and 8 are side views of keys of different constructions.

The stock A is provided with a bore, B, extending inward from one end, which stock is screw-threaded and screwed into the closed end of a cap, C, the other end of which is closed by a circular plate, D, screwed into it, said plate having a central aperture, E, through which the spindle F is passed, said spindle being passed into the bore B in the stock A, and also having a longitudinal bore, G, extending inward from the inner end. The spindle F has a shoulder or offset, which rests against an annular rabbet, H, in the inner surface of the plate D, and around the aperture E. A tubular screw, J, having a rounded head, J, is screwed into the inner end of the spindle F, the head J" resting against a hard steel step, K, in the inner end ,of the bore of the stock. L is an oil-hole. A rod,

M, in the bore of the spindle F has one end passed loosely into the tubular screw J, and the other end of said rod is provided with a rounded head, N, resting against akey, 0, passed through a slot, P, in the spindle F. The cap C has slots or apertures R in the sides, through which the key 0 can be inserted. The key has concaved notches S in the top and bottom edges at its middle, for receiving the curved part of the head N. A spiral spring, T, surrounds the rod M between the end of the screw J and the head N, and said spring presses said head N on the key 0. The inner surface of the plate D is curved upward from the center to two diametrically opposite points, as shown. On the part W of the spindle a chuck is to be placed for holding drills, taps, taper reamers, 82c. \iVhen the stock revolves in relation to the spindle, the key 0 slides on the innersurface of the cam-plate D, and as the ends of the key slide over the opposite raised or cam portions of the cam-plate they are pressed in the direction of the arrow a, as is also the rod M on the key, the inner end of the said rod passing into the hollow screw J. By such movement of the rod M the spring T is compressed. If the tension of the spring is slightly less than the strain required to break the tool in the chuck, the spring can give, and the stock A revolves without revolving the spindle F. As long as the strain on the spindle F is less than the power of the spring T,the spindle revolves with the stock; but the moment the strain on the spindle is too great the spindle is stopped and only the stock is revolved. The elevations in the camplate act as wedges, and whenever there is suificient resistance the wedges force themselves under the edge of the key. A wedge with a slight inclination will force itself under the key when less resistance is offered than would be necessary with a wedge of greater inclination. The key that bears or touches on the cam-plate near its periphery will not only have more leverage on the spindle, but it will require more resistance to cause it to ride or slide over the elevation, as the elevation or inclination is steeper. A key that bears on the cam-plate near the middle will have less leverage on the spindle and only a slight inclination to slide over. The keys are so c0nstructed that they can be reversed so as to bring the other side to bear on the cam-plate,

one side offering more resistance than the other. Ifdesired, the keys may be provided with bearing-points, as shown in Figs. 7 and 8. The key shown in Fig. 8 offers more resistance than the key shown in Fig. 7, the resistance of the two keys being less at m, Fig. 7, greater at m Fig. 7, still greater at m Fig. 8, and greatest at m, Fig. 8. The tension of the spring T must be so adjusted that it is slightly less than the breaking strain of the tool, drill, &c.; but care must be taken that the said tension is not much less than the breaking strain of the tool, as otherwise the spindle would stop when the tool is fully able to overcome the resistance ofl'ered without ing of fine and valuable tools is thus avoided to a great extent.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. In a spindle, the combination, with a chuck-holder, of a cross-piece or key in the same, and a cam-plate against which the key or cross-piece is pressed,substantially as herein shown and described.

2. The combination, with a chuck-holder, of a crosspin or key passed through the same, a spring acting on the said key, and a camplate on which the key is tnrned,substantially as shown and described.

3. The combination,with a revolving chuckholder, of a key passed through the same, a earn-plate on which the key rests, a rod resting on the key, and a spring acting on the rod and pressing it on the key, substantially as herein shown and described.

4. The combination, with the tubular Stock A and the cap ,0, of .the spindle F, the rod M in the same, the key 0, on which the rod M rests, and of the cam-plate D in the cap 0, substantially as herein shown and described.

5. The combination, with the stock A and the cap B, of the spindle F, the tubular screw J, the rod M, the spring T, the key 0, and the cam-plate D in the cap C, substantially as herein shown and described.

6. The combination, with the stock A, having the bore B. of the spindle F in the same, the screw J in the end of the spindle, the step K in the stock, the rod M, the spring T, the key 0, the cap 0, and the cam'plate D in the same,substantiall y as herein shown and described. I

7. The combination,'with a spindle, of a tension mechanism for the same,substantially JAMES HARTNESS.

\Vitnesses:

R. SLoA HOLLIS P. RISLEY. 

